Maybe I' m wrong here, but there' s more software that can actually process 8-bit/16-bit/32-bit files. Many times though it can not display 10-bit colour (same as many monitors cannot). Displaying is different from processing.
Sorry, I was too direct in my earlier posts and caused/showed confusion.
Based on the gradient png linked by
@Superhai, and looking mostly at the grey, by eyeballing my results are:
Does display 10 bit: Photoshop 2022, Lightroom Classic, Pixelmator Pro, Acorn, Aurora HDR 2018, Apple Photos, Safari, Preview.
Only 8 Bit display: Affinity Photo (that surprised me), Digikam, Brave, Firefox.
All the photo editors above can process in 16 bit or better (not sure about Photos).
I have deliberately included some browsers and Preview.
With exception of Aurora HDR 2018, all apps with current version running on macOS 12.5.1 and iMac 2019 27".
So my recommendation for a suitable 10-bit display photo editing app is Pixelmator Pro which is functionally similar to photo editing with Photoshop. But maybe test Photos first as it is free.